Patrick Peterson wasn’t sure who was happier when the Cardinals drafted Tyrann Mathieu last month — Peterson or Mathieu.

On the day it happened, we talked to Peterson just moments after speaking with Mathieu on a conference call, and their emotions ran raw and deep.

“Honestly, this is definitely by far one of the happiest days of my life,” Peterson, the Cardinals’ third-year cornerback said. “It feels like I got drafted all over again when I saw his name pop up across the board.”

Peterson’s relationship with Mathieu goes a lot further than the two simply being former college teammates at Louisiana State. Peterson, who turns 23 in July, has been more like a protective older brother to Mathieu, who turns 21 on Monday.

And that closeness didn’t end when Peterson left LSU and was selected by the Cardinals with the fifth overall pick in the 2011 draft. In many ways, their friendship grew stronger — perhaps out of necessity.

Mathieu, the talented defensive back known as “Honey Badger” because of a viral video of Mathieu at LSU making big plays, had a problem. He couldn’t say no to marijuana, and his addiction ultimately led to his dismissal from the Tigers’ football program.

But despite missing all of last season following numerous failed drug tests and an October arrest for marijuana possession, Mathieu is getting a second chance. And Peterson is largely responsible for it.

Last fall, Peterson made arrangements for Mathieu to move to Pompano Beach, Fla., and live with his parents, Patrick Sr. and Shandra. They provided him with a structured and stable environment, something he was sorely lacking in Baton Rouge.

Mathieu worked out regularly for the elder Peterson, and when the Cardinals’ season ended, Patrick Jr. took over. He counseled Mathieu, mentored him, and flew him to Arizona, where he could help him train for the NFL’s scouting combine. The Cardinals were impressed enough to draft him in the third round. If it works out, Mathieu could find himself in the same defensive backfield with Peterson and standing near him on punt returns.

“For him to have another opportunity to do something he loves is unbelievable,” Peterson said. “Going back seven months ago, he declared his dream was to play with me once again. He said that was definitely his dream, and his dream came true.”

So far, things look positive. But Mathieu will have to prove his worthiness through more than hard work and dedication. He will have to pass frequent random drug tests.

Cardinals General Manager Steve Keim said there might be some “speed bumps” along the way, but clarified that with this comment: “If there are speed bumps, I can promise you that it’s a short leash.”

Peterson stuck his neck on the line for Mathieu, assuring the Cardinals that Tyrann will stay out of trouble.

“I’m more than confident he’s going to be OK,” Peterson said. “He had a couple issues coming out of college, but trust me, that is more than behind him. This is a kid that just wants to play football again. He knows he made mistakes, but football is his life and now that he has the opportunity to do it again, he’ll never let that opportunity slip away from him again.”

But how can be sure?

“Because I’ve been with him,” Peterson said. “I’ve been talking with him for the last nine, 10 months, constantly picking his brain, seeing where he’s at mentally, seeing where he’s at emotionally. The guy’s just ready to play football.

“He made a mistake. He wasn’t in a stable position in his life at the time when he did get caught with the marijuana. But now he understands the importance of being accountable, being a role model. That stuff is behind him.”

Mathieu made a pact not only with himself, but to Peterson, his big brother. If he makes it in the NFL, he knows it will be because of Peterson’s caring friendship and endless help.

“I want to do it for myself. I want to do it for the Cardinals,” Mathieu said. “But I want to do it for Patrick, because Patrick is one of the few who believed in me.”

It’s a beautiful story, assuming Mathieu walks the walk. It will be even better, Keim noted, once Mathieu is able to stand on his own.

“There’s going to be a point in time when they leave this facility,” Keim said, “where Tyrann is going to have to become a grown man and make the right decisions on his own.”

We can only hope that he does.

Reach The Heat Index at bob.mcmanaman@arizonarepublic.com. Follow him on Twitter @azbobbymac and listen to him every Monday at 4:30 p.m. on AZ Sports Talk with Roc and Manuch on NBC Sports Radio AM 1060.

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